BMW 1 Series - Kelleners KS1-S

Kelleners’ KS1-S is an M-badged maverick in 1 Series clothes.

In the days when I lived in England and drove to Germany through France and Belgium, we used to joke that if you blinked while driving quickly, you would miss Belgium. Luxembourg is even smaller than Belgium, so you really do have to watch that you don’t blink while driving quickly through it.

The upside is that the Grand Duchy of Luxembourg has enlightened planning authorities. Thus, avant-garde houses like the one in Remich that I thought would make a suitable backdrop for Kelleners Sport’s maverick BMW 1 Series M conversion, are as much the rule as the exception here.

In the old days, the journey to the German-Luxembourg border from Kelleners Sport’s former HQ in Dinslaken in Germany’s dreary Ruhr industrial region would have been a fair trek. But today it took just 20 minutes. The reason for this is that in 2010, Kelleners Sport came under the same ownership as Mercedes tuner Carlsson, and moved their whole operation—lock stock and barrel—to Merzig.

In the heart of the sunny, wine-growing region of Germany that borders France and Luxembourg, Merzig has some superb driving cross-country roads as well as the customary unrestricted stretches of autobahn. This is the perfect neck of the woods to make and drive fast cars.

BMW’s manual-only 1 Series M is a regular pocket rocket out of the box. On paper, its power-to-weight ratio is only slightly down from that of the M3. However, the entry-level M car is lighter overall, and its twin-turbocharged straight-six is more torque rich than the naturally aspirated V8. Its greater mid-range urge means that in the real world away from stopwatches and dragstrips, a skilful 1 Series M driver can embarrass an M3 jockey who is not paying attention to his potential predicament.

The Kelleners Sport conversion ramps the power up to 410 hp and 407 lb-ft of torque. With an extra 70 hp and 75 lb-ft of torque on top of the factory output, the Kelleners Sport KS1-S will effortlessly drive away from an M3 in a straight line. In fact, the tweaked motor has so much mid-range thrust that it also poses a serious threat to junior league supercar pilots whose mounts wear the prancing horses of Modena and Stuttgart. This is a real stealth machine for reasonable money.

In percentage terms, this is a 20 percent increase in power and 22.2 percent increase in torque, a modest increase that is well within the capability of the stock drivetrain to handle. Significantly, this Stage 1 upgrade makes more of a difference to the way the car drives than the numbers would lead you to believe.

Being turbocharged, the stock motor with its single throttle body and plenum induction system does not respond as sharply to a demand for action as the naturally aspirated M3 power unit with its single throttle-per-cylinder setup. And no thanks to stringent drive-by noise regulations in countries like Switzerland and Germany, the ear candy production potential of the factory exhaust is also seriously restricted. Since enthusiasts hold that the way an engine responds and sounds makes up half the character of a sporting car, these are serious problems.

On a quiet stretch of suburban road, I got my first indication of what I was in store for when I was able to extend the car in Second gear. Oh my God!

The changes wrought by the Kelleners Sport conversion on both fronts makes a remarkable difference to the way the car drives and sounds. To wit, they transform it from a fast but clinically efficient driving machine into one that makes the hair on the back of your neck stand up every time you use the throttle’s full travel.

All of today’s electronic management controlled engines are dialed back from their full potential by anything from 20 to 50 percent. This is done partially to retain headroom for future upgrades as well as to safeguard the motor from poor fuel quality and thermal stress in hot climates.

Tuners can take advantage of this built-in headroom, especially in Europe where good quality high-octane fuel between 98 and 100 RON octane is readily available. This allows them to dial in more ignition advance at lower rpm, which noticeably improves pickup.

Knock sensors are very advanced these days, and can instantly dial back the ignition at the threshold of detonation almost to the point where you are unaware it has occurred. Kelleners Sport’s electronics wizard makes full use of these attributes as well as turning up the boost slightly.

The final piece of the puzzle is the more efficient free-flow exhaust silencer box whose business end shows four highly polished 83mm diameter end pipes to the world. While the system is only worth a couple of extra horses, it reduces the backpressure that is the bane of forced-induction motors, and endows the exhaust gases with a more serious baritone voice as they make their frantic bid for freedom.

Now, when you blip the throttle at idle, the revs rise and fall as if the engine has one throttle per cylinder and a single-mass flywheel, and your ears pick up a sharp whoop from the exhaust pipes. Around town the engine is unchanged from stock in docility, which means your granny could drive it to the shops without the slightest inkling of the mass mayhem she would unleash if her foot slipped.

On a quiet stretch of suburban road, I got my first indication of what I was in store for when I was able to extend the car in Second gear. Oh my God! I abandoned all thoughts of taking the scenic route to the Luxembourg border and headed straight for the autobahn.

Coming off the slip road, I gave it death in Third gear and was rewarded with a strong and relentless gushing of power and torque that would leave most so-called performance cars floundering in this mini-M car’s wake. The twin-turbo straight-six motor now feels as if it’s breathing through bigger lungs, which in itself makes a positive difference to the way it attacks the upper part of its working range.

More than that, the instant response gives no indication whatsoever that this motor is turbocharged. If you did not know, you might even believe that there was a 5.0-liter naturally aspirated motor under the bonnet, such is the instant response and strong surge of power and torque on tap. Even coming off the throttle and straight back on brings instant response, with none of the expected hesitation you get from a turbo motor that has just dumped all of its boost.

The stock 1 Series M motor is borderline in feel and soundtrack, and a notch behind its naturally aspirated peers in this respect. The small but significant changes that Kelleners Sport has wrought to its response and character more than make up for what enthusiasts initially perceived as a step backwards. If this is the future of M car motors, then count me in.

A factory fresh 1 Series M looks just fine on its 9x19 and 10x19 wheels shod with 245/35ZR19 and 265/35ZR19 Michelins. They fill the big arches nicely and give the car a pretty intimidating stance. That stance is further improved by the 25mm lower ride height conferred by the height adjustable Kelleners Sport coilover suspension kit whose dampers feature independently adjustable compression and rebound control.

Complementing the uprated suspension is a footwear choice of either 19-inch alloys that reuse the stock rubber, or the 20-inch alloys fitted to this demo car. Sized 9-inches wide in front and 10-inches in the rear, with 245/30ZR20 and 265/30ZR20 tires, these wheels look terrific at first glance, but as I quickly discovered, they also have a dark side.

After a second look, these 20s are actually a shade too big visually, which makes the car look like a caricature of itself. The rubber band tires also negatively affect the ride and handling. A bouncy secondary ride is one thing, but the fact that the car feels like it is over-sprung on bumps taken at speed does not bode well for stability when you’re really pressing on. A nightmare situation would be sudden departure from a bumpy corner in the wet because you discovered fresh air under the tires.

Kelleners Sport told me that customer demand led them to offer larger wheels than stock. While I can understand that they want to emphasize that they have a tuned car, this is one instance where engineering and marketing are seriously at odds. To make sure I was pinning the blame on the right party, I asked to try the 19-inchers, and I was not disappointed. Not only did they look better, they also transformed the ride and handling, allowing the uprated suspension to shine.

The ride is only about 10 percent firmer than stock, but the reduced roll and sharpened turn-in make full use of the mechanical grip of the stock Michelin rubber. They extend the driver’s confidence window by taking that last bit of slack out of the way the car settles into a bend and exits when you start to accelerate out. They also send clearer messages, making flirting with the limit and beyond a more enjoyable experience. This extra feedback is crucial to using the extra power and torque to the full without overwhelming the chassis. Where the 20s provide more mechanical grip on a perfectly smooth road, they were less transparent in their feedback when approaching the limit.

The electronically controlled M Differential works perfectly with the extra power, and the powerful factory brakes are fine for road use although track day junkies will probably need harder pads or a complete brake upgrade.

Other than the bigger wheels, the only other external change is the neat front spoiler lip that helps to reduce lift over the front axle at speed. In combination with the lower ride height, the car felt hands-off stable at 150 mph, so it obviously works.

Kelleners Sport’s trim shop subtly spruced up the cabin with a bespoke black and white leather and Alcantara re-trim. This features subtle anthracite Alcantara inserts between the black and white leather in the seats, white contrasting stitching on the black leather and Alcantara instrument binnacle hood. Alcantara is also used on the door trim inserts and upper and lower sections of the steering wheel, and for the gear lever and handbrake boots. White lacquered dashboard and door pull trims eschew the expected use of carbon fiber or black piano lacquer. Final touches are the Kelleners Sport logos embroidered on the headrests and floor mats.

While I felt that the KS1-S strikes the kind of perfect balance between power and handling that makes a great daily driver, Kelleners said that they have been very conservative with this first step, and that there is more to come.

They already have an engine with a larger intercooler and revised software on the dyno, and are looking at 440 hp and around 420 lb-ft of torque. That ought to be enough to keep the power junkies happy.